Rotary mower engine muffler



June 30, 1964 w. H. PRICE ETAL ROTARY MowER ENGINE MUFFLER 3Sheets-Sheet 1 Filed April 17, 1963 INVENTORS. WARREN H. PR/ce BY VERNONR. KAuFMAN June 30, 1964 w. H. PRICE ETAL ROTARY MowER ENGINE: MUFFLER 3Sheets-Sheet 2 Filed April 17, 1963 INVENToRs. WARREN H. PRICE BY VERNONR. KAUFMAN A-r-roRNEYs June 30, 1964 w. H. PRICE ETAL ROTARY MowERENGINE MUFFLER Filed April 17, 1965 Z0 /5 ...'...bnn

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WARREN H. PRICE VERNON R. KAUFMAN ATroRNE-Ys United StatesPatent O3,138,910 RTARY MGWER ENGINE MUFFLER Warren El. Price, South Milwaukee,and Vernon R.`Kauf man, Racine, Wis., assignors to .IacohsenManufacturing Company, Racine, Wis., a corporation of Wisconsin FiledApr. 17, 1963, Ser. No. 273,669 Claims. (Cl. 56-25.4)

This invention relates generally to rotary mowers and more particularlyto an improved muiiier construction for the internal combustion engineoi such a mower.

A seriousproblem in prior art devices of this character has been that ofheat dissipation from the engine, that is, the concentration of heattransmitted to the cranltcase.

Another problem has been that of noise of the muflier, due among otherthings, to vibration and exingof the sheet metal parts, and vibrationtransmitted through still other parts.

Accordingly, the present invention provides a rotary mower mufflerconstruction which will greatly reduce the above-mentioned difficulties.

One aspect of the present invention relates to a mufiler constructionfor a rotary mower in which the engine exhaust is mutlled through aseries of chambers and is iinally passed through the grass conveyingtunnel of the mower all in a particularly eicient and effective manner.As the exhaust is discharged into this tunnel, there is no back pressureagainst it, and in fact it is introduced into an area of sub-atmosphericpressure, which results in par'- ticularly good etliciency of engineoperation.

The present muiller construction iinds exceptional utility and closecooperation with a particularly shaped wind tunnel, to thereby result inan etiicient conveying action of the exhaust.

The rotary mower mufer construction provided by the present inventiondivorces the engine to a considerable extent from the housing and insuch a. manner that (l) heat is not readily conducted back to the enginecrankcase, (2) the engine mounting and the mower housing, particularlyat the muffler junction, can shift relative to one another within limitsas required by expansion and contraction of the parts, (3) the saidjuncture is well in# sulated against heat transfer, and (4) ahorizontally large dead area is provided between the engine mounting andthe mower housing which serves to effectively dampen much noise andvibration.

These and other objects and advantages will appear more fully as thisdisclosure progresses, reference being had to the accompanying drawings,in which:

FIGURE l is an elevational View of a mower embodying the presentinvention, the view being partially in section and taken along line 1-1in FIGURE 2;

FIGURE 2 is a bottom view of the mower housingk shown in FIGURE l, butwith the rotary blade and muffler cover removed and on a reduced scale;j

FIGURE 3 isa fragmentary, vertical sectional view taken along line 3-3in FIGURE 2, but on an enlarged scale; 1

FIGURE 4 is a fragmentary, vertical- View, in section and taken alongeither one of lines 4--4 in FIGURE 2, but on an enlarged scale;

FIGURE 5 is a fragmentary, vertical view, in section and taken alongline 5-5 in FIGURE 2, Vbut on an enlarged scale;

FIGURE 6 is arfragmentary, vertical view, in section l and taken alongline 6 6 in FIGURE 2, but on an enlarged scale; and

FIGURE 7 is a top plan view of the muler cover shown in FIGURE l, but onan enlarged scale.

Referring in greater detail to the drawings, the mower housing H is castas one piece and has a generally vertical outer wall 1, a generallyvertical inner wall 2, and

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a top wall El which together define a tunnel T of inverted and generallyU-shape cross-sectional form. As shown in FIGURE 2, these walls form acircular tunnel for the majority of their length and then iiaretangentially beginning at about point 5. Walls l and 2 become ofincreasingly greater height as they extend from point 6 and then in adirection of travel of the rotary blade unit B, as indicated by thecurvilinear arrow, until they terminate at the discharge end 7 of thettmnel.

A tunnel T is thereby provided which is of constant width until ittangentially flares adjacent its discharge end, and is of increasinglygreater height for its entire length.

The action of the cone-shaped blade assembly B as it rapidly rotates inthe housing creates an area of subatmospheric pressure at the beginningof the tunnel as indicated generally at 6.

The-housing also has an upper, annular ring-like hat surface 8 (FIGURESl and 5) of rather narrow width and in which are four circumferentiallyspaced apertures 9 which receive the engine mounting bolt means lil.

A downwardly extending and relatively wide, dishshaped central portion11 also forms part of the housing and has a central aperture 12, throughwhich the central portion 13 of the blade assembly B extends.

If a more complete description of the housing is deemed to be eithernecessary or desirable, reference may be had to the co-pending U.S.application Serial Number 225,791, led September 24, 1962, and nowPatent No. 3,112,596 issued December 3, 1963, and entitled, Rotary MowerCleansing Means.

An internal combustion engine E is mounted by its base l5 and bolt meansIt) to the surface 8 of the housing. The underside of the base has araised boss 16 (FIG. 5)

around each of the four apertures 17 which extendy An air gap 18 isprovided between the majority of the engine base and housing, and thisgap permits escape of heat from the otherwise substantially enclosedspace 2l) between the upwardly extending inverted dish-shaped base andthe complementary downwardly extending, dishshaped portion 11 of thehousing.

This circular Ztl has a diameter greater than one-half that of the outerdiameter of the surface 8, and provides a cushioning effect for theVibration and noise generated by the engine. Stated otherwise, thecircular portion 1l. has a diameter greater than one-half of thediameter of the circular inner lwall 2, and the height of said portion11 is less than one-half the height of said housing.

The vertical drive shaft 22 of the engine is fixed by the cap bolt 23and key 24 in driving relationship with portionA 13 of the blade4assembly. Aclearance space exists between portion 13 and aperture l2 ofthe housing.

-In order for any heat from the housing to be conducted back up to theengine, it must travel through portion 11, through the narrow surface S,through bosses 16 and then through the base itself.

Furthermore, by providing a large space 20 at the central portion of thehousing, various makes of engines (not shown) can be accommodated, someof which may as engine, base and housing may become quite hot in thislocation of the exhaust passage, considerable shifting or relativeexpansion of these parts may occur in this area without damage thereto.In other words, a tight se'al is provided between exhaust passages 30,31 and 32, but the parts are not rigidly held together here.

The mufiier area M in general is defined by the inside of inner wall 2,the central portion 11, the top side of the housing, and a muffler cover40 which is secured by bolts 41 threaded into apertures 42 in theunderside of the housing. This cover is formed as a sheet metal stampingand its outer peripherally flanged edge 43 abuts tightly in thecounterbore 44 at the lower end of wall 2. The generally flat anddish-shaped cover has a central opening which is defined by an upwardlyturned edge 45 that seats snugly around the lower shouldered end ofportion 11.

It will be noted that the cover has a crowned or raised portion 46extending upwardly into the muffler area and located directly below theexhaust passage 32. As indicated in FIGURE l, by the arrows, the highvelocity exhaust `as it is directed downwardly is deflected in differentdirections by the raised portion. This prevents vibration and flexing ofthe sheet metal cover and as well as thereby reducing the noise level,it also disperses the exhaust in the muflier.

A series of separate mufller chambers C1, C2, C3 and C4 are definedbetween the underside of the housing, and the muflier cover by means ofthe radial ribs 50, 51, 52, 53, 54 and S5, and the arcuate ribs 56 and57. Chambers C1 and C2 are in communication with one another throughpassage 60; chamber C2 communicates with chamber C3 via passage 61located between radial ribs 51 and 52; chamber C3 and chamber C4 havepassage 60 therebetween; chamber C4 is shielded from chamber C1 by thefull rib 55 (FIGS. 2 and 6).

In this manner a tortuous path is formed, as indicated by the dottedarrows in FIGURE 2, for the exhaust, and it is discharged into thetunnel via small apertures 65 in the cover.

The exhaust enters the tunnel adjacent its small or beginning end wherethere is sub-atmospheric pressure and then travels through the longtunnel which is constant width, ever increasing height in cross sectionand acts as a final muffler chamber.

By the time the exhaust has completed the above described tortuous paththrough the various chambers, it has been greatly reduced in sound andvelocity.

The upper dish-shaped member 67 of the blade' assembly B complements theshape of the muflier cover. As shown in FIGURE l, member 67 is nested inthe cover and rotates directly beneath it.

The relatively fiat muffler construction which extends across themajority of the diameter of the housing and is located within the innerwall that in part defines the clippings tunnel, functions to enclose thecentral portion of the interior of the mower housing. As a result, theblade assembly is much more efficient in picking up and carryingclippings than it would otherwise be if the central portion of the mowerhousing was open and unrestricted.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention:

We claim:

1. A rotary mower having a housing including downwardly extending andgenerally concentric circular, inner and outer walls which togetherdefine an annular tunnel for the confinement and passage of clipping forultimate discharge from the mower; said tunnel being of a relativelysmall cross section at its beginning end and increasing in cross sectiontowards its discharge end, said v inner wall terminating in a lower edgethat is approximately half-way below the height of said housing; saidhousing also having a central, downwardly extending and at dish-shapedportion which terminates in a lower edge that defines a central opening;said dish-shaped portion having a diameter that is greater than one-halfthe diameter of said circular inner wall, said portion having a heightless than one-half of the height of said housing, a generally fiat andinverted dish-shaped cover secured between and to the lower edges ofsaid inner wall and portion to thereby define a mufiier chamber withsaid inner wall and dish-shaped portion, an engine base secured on topof said housing so as to define with said portion a substantiallyenclosed space for insulating an engine carried on said base from saidportion, an exhaust passage from said engine and in communication withsaid chamber, and apertures in said cover placing said chamber inexhaust discharging communication with the small beginning end of saidtunnel.

2. A rotary mower having a housing including downwardly extending andgenerally concentric circular, inner and outer walls which togetherdefine an annular tunnel for the confinement and passage of clippingsfor ultimate discharge from the mower; said tunnel being of a relativelysmall cross section at its beginning end and increasing in cross sectiontowards its discharge end, said inner wall terminating in a lower edgethat is at least half-way below the height of said housing; said housingalso having a central, downwardly extending and flat dish-shaped portionwhich terminates in an opening defining lower edge; a generally flat andinverted dish-shaped cover secured between and to the lower edges ofsaid inner wall and portion to thereby define a muffler chamber withsaid inner wall and dish-shaped portion, an exhaust passage from saidengine and in communicatition with said chamber, and apertures in saidcover placingsaid chamber in exhaust discharging communication with thesmall beginning end of said tunnel.

3. A rotary mower having a housing including downwardly extending andgenerally concentric circular, inner and outer walls which togetherdefine an annular tunnel for the confinement and passage of clippingsfor ultimate discharge from the mower; said tunnel being of a relativelysmall cross section at its beginning end and increasing in cross sectiontowards its discharge end, said inner wall terminating in a lower edgethat is at least half-way below the height of said housing; said housingalso having a central, downwardly extending and fiat dish-shaped portionwhich terminates in an opening defining lower edge; a generally flat andinverted dishshaped cover secured between and to the lower edges of saidinner wall and portion to thereby define a mufller chamber with saidinner wall and dish-shaped portion, an engine base secured on top ofsaid housing so as to define with said portion a substantially enclosedspace for insulating an engine carried by said base from said portion,an exhaust passage from said engine and in cornmunication with saidchamber, and apertures in said cover placing said chamber in exhaustdischarging communication with the small beginning end of said tunnel.

4. A rotary mower having a housing including a downwardly extending,circular, inner wall which terminates in a lower edge that issubstantially half-way below the height of said housing; said housingalso having a central, downwardly extending and dish-shaped portionwhich terminates in a lower edge that defines a central opening; aninverted dish-shaped cover secured between said lower edges to therebydefine a mufiier chamber with said inner wall and dish-shaped portion,an engine base, an engine mounted on said base, said base secured on topof said housing so as to define with said portion a substantiallyenclosed space for insulating said engine from said portion, a driveshaft extending downwardly from said engine and through said space, anda blade assembly secured to the lower end of said shaft, said assemblyincluding a dish-shaped member which complements and is nested in saidcover for rotation directly therebeneath.

5. A rotary mower having a housing including downwardly extending andgenerally concentric circular, inner and outer walls which togetherdefine an annular tunnel for the confinement and passage of clippingsfor ultimate discharge from the mower; said inner wall terminating in alower edge that is at least half-way below the height of said housing;said housing also having a centrai, downwardly extending and atdish-shaped portion which terminates in a lower edge that denes acentral opening; a generally flat and inverted dish-shaped cover securedbetween and to the lower edges of said inner wall and portion to therebydefine a muler chamber with said inner wall and dish-shaped portion, anengine base, an engine mounted on said base, said base secured on top ofsaid housing so as to dene with said portion a substantially enclosedspace for insulating said engine from said portion, a drive shaftextending downwardly from said engine and through said space, and ablade assembly secured to the lower end of said shaft, said assemblyincluding a dish-shaped member which complements and is nested in saidcover for rotation directly therebeneath.

References Cited in the iile of this patent UNITED STATES PATENTS2,675,662 Kroll Apr. 20, 1954 2,774,439 Chesser Dec. 18, 1956 v FOREIGNPATENTS 220,092 Australia Feb. 6, 1959

1. A ROTARY MOWER HAVING A HOUSING INCLUDING DOWNWARDLY EXTENDING ANDGENERALLY CONCENTRIC CIRCULAR, INNER AND OUTER WALLS WHICH TOGETHERDEFINE AN ANNULAR TUNNEL FOR THE CONFINEMENT AND PASSAGE OF CLIPPING FORULTIMATE DISCHARGE FROM THE MOWER; SAID TUNNEL BEING OF A RELATIVELYSMALL CROSS SECTION AT ITS BEGINNING END AND INCREASING IN CROSS SECTIONTOWARDS ITS DISCHARGE END, SAID INNER WALL TERMINATING IN A LOWER EDGETHAT IS APPROXIMATELY HALF-WAY BELOW THE HEIGHT OF SAID HOUSING; SAIDHOUSING ALSO HAVING A CENTRAL, DOWNWARDLY EXTENDING AND FLAT DISH-SHAPEDPORTION WHICH TERMINATES IN A LOWER EDGE THAT DEFINES A CENTRAL OPENING;SAID DISH-SHAPED PORTION HAVING A DIAMETER THAT IS GREATER THAN ONE-HALFTHE DIAMETER OF SAID CIRCULAR INNER WALL, SAID PORTION HAVING A HEIGHTLESS THAN ONE-HALF OF THE HEIGHT OF SAID HOUSING A GENERALLY FLAT ANDINVERTED DISH-SHAPED COVER SECURED BETWEEN AND TO THE LOWER EDGES OFSAID INNER WALL AND PORTION TO THEREBY DEFINE A MUFFLER CHAMBER WITHSAID INNER WALL DISH-SHAPED PORTION, AN ENGINE BASE SECURED ON TOP OFSAID HOUSING SO AS TO DEFINE WITH SAID PORTION A SUBSTANTIALLY ENCLOSEDSPACE FOR INSULATING AN ENGINE CARRIED ON SAID BASE FROM SAID PORTION,AN EXHAUST PASSAGE FROM SAID ENGINE AND IN COMMUNICATION WITH SAIDCHAMBER, AND APERTURES IN SAID COVER PLACING SAID CHAMBER IN EXHAUSTDISCHARGING COMMUNICATION WITH THE SMALL BEGINNING END OF SAID TUNNEL.